CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

J.L.M. wrote:
> I have been writing some programs that use the Nef_polyhedron_3 and
> Minkowski_sum_3 portions of the CGAL library. I have discovered a number 
> of assertions with various input shapes. The attached backtrace shows 
> one example problem. I have also attached a small example program, and 
> the input shapes. The l-shape is shown in the attached jpeg file.
>
> This problem shows up in both CGAL 3.7 and 3.6.1. I am using GCC 4.5.1
> on Arch Linux with kernel version 2.6.36.
>
> I think this is a bug, since it does not occur with other input shapes. 
> I would be very grateful if someone can help me fix it since the 
> Minkowski_sum_3 is essential to my research.
>
> Thank you for your time.
>
> Jason M'Sadoques
>
>
>
> ------------------------------------------------------------------------
It seems their is a problem in boundary function.

If I replace:
  Nef_polyhedron_3 container_boundary(container.boundary());
by
  Nef_polyhedron_3 container_boundary(container);

Your program runs fine (with your data, the call to boundary is
superfluous).

Note that as you are then reusing "container", you need to make a copy
of it
(see 
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Minkowski_sum_3/Chapter_main.html)

Note also that the difference you are computing will be empty as the 
Minkowski sum contains "container".

Finally, note that facets of your cube are clockwise oriented while the 
usual convention is to use counterclockwise oriented faces in off files.

I'll try to find a fix to boundary function and will post it here.

S.